1. Field of the Invention
This invention pertains to safety apparatus, and more particularly to apparatus for preventing a movable carriage from rolling down an inclined surface.
2. Description of the Prior Art
Mobile storage systems for storing books and files in libraries and offices are well known. The systems include at least one elongated and wheeled bookshelf-like carriage which rolls along rails embedded in the building floor. The carriage may be moved along the rail either manually or under electric power.
Under certain circumstances, the system rails cannot be installed in the floor in a level attitude. In that situation, it is nececcary to automatically lock a power movable carriage in place immediately upon de-energizing the drive motor so as to prevent uncontrolled rolling and possible injury to a person in its path. Further, the carriage must remain locked against rolling until the driving force is reapplied.
To lock a carriage in place, various devices have been developed. For example, U.S. patent application Ser. No. 575,216 illustrates a rack and spring loaded locking Bar. U.S. Pat. No. 4,523,794 discloses a reciprocable pin type locking device. However, the devices of the two mentioned patent applications are designed for locking manually operated and level carriages which are stationary prior to engaging the respective locks. They are not intended to stop a carriage which is rolling without control after the driving force has been removed.
A need exists for a safety brake which is applied immediately upon stopping a movable carriage and which remains applied until the carriage is restarted.